VARIATIONS IN VENOMS 155 



75^, H tciniK'i'atiirc that leaves tlie neurotoxin and lieiiiolysin uiiiii- 

 jured. Its endotlieliolytic action is shown in the glomerular capil- 

 laries, where it causes hemorrhage and hematuria (Pearce)."' 



Variations in Venoms. — In distribution among the various poison- 

 ous reptiles these toxins seem also quite distinct from one another, 

 which explains the difference in the et't'ects of bites b}' snakes of various 

 kinds. Cobra venom contains chiefly neurotoxin, hence the symp- 

 toms of cobra bite are largely of nervous origin, with but little local 

 tissue change. Rattlesnake venom owes its effects chiefly to hemor- 

 rhagin, hence the marked local necrosis and extravasations of the 

 blood, and. the generalized hemorrhages ; the nervous effects following 

 viper bite are probably, in part, due to hemorrhages in the nervous 

 tissue. Cobra venom produces great hemolysis and little agglutina- 

 tion. Rattlesnake venom has relatively little agglutinative or hemo- 

 lytic power. Water moccasin and copperhead venoms are more ag- 

 glutinative than either, and intermediate in hemolytic strength; they 

 cause much local tissue destruction. 



The exact action of cobra venom on various centers and orfj^ans has been 

 studied by Elliot. 4i It raises blood pressure when in dilution of 1 : 10,000,000, 

 by contractinjj vessels and stimulating the Iieart; low lethal doses kill by para- 

 lyzing the respiratory center. 



Krait {Bunf/arus c(rrulites) venom acts similarly, but less powerfully, and 

 cannot be neutralized by Calmette's antivenin.^2 



Sea-snake venoms are by far the most poisonous of all. For Enhj/drina valalca- 

 dien the lethal dose for rabbits is 0.00006 gram per kilo body weight. It acts by 

 vaaus stimulation and paralysis of respiratory centers and of motor nerve- 

 endings.43 



Russell's viper (Dahoia T'lissellii) owes its effects chiefly to intravascular clot- 

 ting, according to Lamb and Hanna,** and contains no neurotoxin. It is not 

 neutralized l)y Calmette's antivenin. The clots are due to agglutination and con- 

 tain no fibrin (Flexner). 



The "Gila Monster" {Heloderma- suspectum) seldom causes serious poisoning 

 in man, but may kill small animals, such as frogs. -is Its poison is only slightly 

 hemolytic, but produces degenerative changes in the nervous system (Langniann). 

 The hemolysin is activated by lecithin (Cooke and Loeb). An elaborate series of 

 studies by Leo Loeb and his associates give all the known facts concerning the 

 Gila Monster.45a 



Loss of Bactericidal Powers. — The frequency of marked and per- 

 sistent sloughing and suppuration at the site of snake-bites, particu- 

 larly from the vipers, and the common termination in sepsis, was 

 attributed by Welch and Ewing *^ to a loss of bactericidal power of 



4o,T(nir. Exper. Med., 1009 (II), .5.32. 



41 Lancet, 1904 (i), 715. 



42 Elliot, Sillar, and Carmichael, Lancet, 1904 (ii), 142. 



43 Eraser and Elliot, Lancet, 1904 (ii), 141; also Rogers, Jour, of Physiol., 

 190.3 (30), iv. The above are also given completely in the Philosophical Trans- 

 actions of the Roval Societv, 1904-5, vol. 187. 



44, Jour, of Patli. and Bact., 1902 (8), 1. 



45 Thorough studv bv Van Denburgli and Wright, Amer. .Toin\ of Plivsiol., 

 1900 (4), 209. 



45a Carnegie Inst. Publication Xo. 177, 191.3. 



46 Lancet, 1894 (1), 1236; Ewing, ]\Ied. Record, 1894 (45), 66,3. 



